What happens to police officers who use excessive force, tamper with evidence or sexually harass someone? In California, internal affairs investigations were kept secret from the public — until a recent transparency law unsealed thousands of files. On Our Watch is a limited-run podcast from NPR and KQED that brings you into the rooms where officers are interrogated and witnesses are questioned to find out who the system of police accountability really serves, and who it protects. New episodes drop weekly, starting Thursday, May 20.